An investigation into the stability and sterility of citric acid solutions used for cough reflex testing

Falconer, James R., Wu, Zimei, Lau, Hugo, Suen, Joanna, Wang, Lucy, Pottinger, Sarah, Lee, Elaine, Alazawi, Nawar, Kallesen, Molly, Gargiulo, Derryn A., Swift, Simon and Svirskis, Darren (2014) An investigation into the stability and sterility of citric acid solutions used for cough reflex testing. Dysphagia, 29 5: 622-628. doi:10.1007/s00455-014-9558-1

Author Falconer, James R.
Wu, Zimei
Lau, Hugo
Suen, Joanna
Wang, Lucy
Pottinger, Sarah
Lee, Elaine
Alazawi, Nawar
Kallesen, Molly
Gargiulo, Derryn A.
Swift, Simon
Svirskis, Darren
Title An investigation into the stability and sterility of citric acid solutions used for cough reflex testing
Journal name Dysphagia   Check publisher's open access policy
ISSN 1432-0460
Publication date 2014-09-28
Year available 2014
Sub-type Article (original research)
DOI 10.1007/s00455-014-9558-1
Open Access Status Not Open Access
Volume 29
Issue 5
Start page 622
End page 628
Total pages 7
Place of publication New York, NY, United States
Publisher Springer
Language eng
Subject 2733 Otorhinolaryngology
2715 Gastroenterology
3616 Speech and Hearing
Formatted abstract
Citric acid is used in cough reflex testing in clinical and research settings to assess reflexive cough in patients at risk of swallowing disorders. To address a lack of knowledge in this area, this study investigated the stability and sterility of citric acid solutions. Triplicate solutions of citric acid (0.8 M) in isotonic saline were stored at 4 ± 2 °C for up to 28 days and analysed by high-performance liquid chromatography. Microbiological sterility of freshly prepared samples and bulk samples previously used for 2 weeks within the hospital was determined using a pour plate technique. Microbial survival in citric acid was determined by inoculating Staphylococcus aureus, Escherichia coli, or Candida albicans into citric acid solution and monitoring the number of colony-forming units/mL over 40 min. Citric acid solutions remained stable at 4 °C for 28 days (98.4 ± 1.8 % remained). The freshly prepared and clinical samples tested were sterile. However, viability studies revealed that citric acid solution allows for the survival of C. albicans but not for S. aureus or E. coli. The microbial survival study showed that citric acid kills S. aureus and E. coli but has no marked effect on C. albicans after 40 min. Citric acid samples at 0.8 M remained stable over the 4-week testing period, with viable microbial cells absent from samples tested. However, C. albicans has the ability to survive in citric acid solution if inadvertently introduced in practice. For this reason, in clinical and research practice it is suggested to use single-use aliquots prepared aseptically which can be stored for up to 28 days at 4 °C.
Keyword Citric acid
Cough reflex testing
Deglutition disorders
Tussigenic challenge
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Pharmacy Publications
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Citation counts: TR Web of Science Citation Count  Cited 2 times in Thomson Reuters Web of Science Article | Citations
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